We've recently changed in one of our offices the computers to Windows 10 and installed Quark 2015, when we try to open documents created in Quark 9 (from other offices) some numbers (1,2,7,8) of the keyboard doesn't work (the numeric keyboard works).
It works on any other application, so it's not a keyboard issue and it's the same behavior in 3 different computers.
If we create the document on Quark 2015 it also works properly.
Also the O letter is not working unless we press the shift key.

I believe these keypad numbers are assigned to the Style Sheets that's why you are unable to type these.
Please do the following:
1: Open the project in which you are facing the issues.
2: Open Style Sheet Palette (Windows > Style Sheets)
3: And see if any of these style sheets shows numbers in the palette.